This invention relates to a carpet seaming roller tool. It relates particularly to a roller tool which is effective to draw two adjacent sections of carpet together in a hot melt adhesive seaming operation during both pushing and pulling movement of the roller tool forward and backward along the seam.
Most carpet installations are done using a hot melt carpet seaming tape in a face seaming operation. In the face seaming operation the two sections of carpet are arranged side by side, the adjacent edges of the two sections of carpet are raised up, and a tape containing a hot melt adhesive is placed beneath the edges of the two sections of the carpet to be seamed. A heating iron is moved along the upper surface of the tape to heat the hot melt adhesive to a molten state, and the lower surfaces of the carpet sections at the seam are then pressed down onto the heated, hot melt adhesive while the adhesive is in a molten or liquid state. A carpet roller tool is usually used to insure that the edges of the carpet are pressed firmly into the hot melt adhesive so that the adhesive is pressed into and around the fibers of the undersurface of the carpet to provide a strong bond between the carpet section and the adhesive and (through the adhesive and the tape) to the other section of the carpet on the opposite side of the seam.
The roller tool used in the prior art had a single, straight axle and a number of toothed discs mounted for rotation on the axle. The teeth on the discs help to penetrate through the pile of the carpet to exert pressure and traction on the woven or fibrous backing material of the carpet. The straight axle roller tool as used in the prior art thus served the primary function of pressing the two carpet sections at the seam firmly into contact with the underlying hot melt adhesive as the roller tool was rolled back and forth along and above the seam.
The seam formed in the face seaming of carpet sections is a butt joint. It is of course desirable to have a tight seam so that hot melt adhesive does not extrude up through the seam and into the pile of the carpet, because extruded adhesive could detract from the appearance of the seam.
Maintaining a tight butt seam is also important in wallpapering, and roller tools have been disclosed in that art for drawing two sections of material together in a tight butt seam at the same time that one of the sections of material is being pressed against adhesive beneath the seam. U.S. Pat. No. 2,693,893 to Rice et al shows a tool having an axle formed with two sections which are slightly inclined to one another so that rollers mounted on two sections of the axle are disposed side by side at a slight angle of inclination with respect to each other. When the tool shown on the Rice patent is moved in one direction, the angled inclination of the two rollers draws the two sections together at the seam. When the roller tool of the Rice et al patent is moved in the other direction, the angled inclination of the two rollers spreads the two sections of the material apart at the seam.
Norwegian Pat. No. 80213 also shows a roller tool having a single axle with two sections inclined at an angle with respect to one another so that rollers mounted on the axle sections produce the same drawing together or spreading apart action as the roller of the Rice et al patent. U.S. Pat. No. 4,224,726 to Walker shows a roller tool for carpet seaming operation using the axle construction of the Rice et al and Norwegian wallpaper tool patents. The Walker patent replaced the rubber rollers of the Rice and Norwegian wallpaper roller tool patents with the toothed discs of the prior art hot melt adhesive carpet seaming roller tools to enable the Walker patent roller tool to produce the same action on carpet sections as the wallpaper roller tools produced on wallpaper strips.
In carpet seaming operations the two sections of carpet are relatively heavy, and there usually is no occasion to want to move the sections apart from one another at the seam. Instead, the objective in carpet seaming is generally to maintain a tight seam. If there is any gap in the seam (because of any local variations in cutting of the edge of the carpet or whatever), the installer would want to close that gap (to prevent the extrusion of hot melt adhesive up through the gap and the detrimental effect on appearance as noted above) rather than to move the sections of carpet apart to increase the gap in the seam.
There is another problem which is peculiar to the carpet seaming operation, and that problem relates to the relatively short open time of the hot melt adhesive. A carpet installer has about four seconds in which to work the backing of the carpet sections down into the hot melt adhesive after the hot melt adhesive has been heated to a molten state. After that period of time the hot melt adhesive sets up to a stage where the fibers in the backside of the carpet section cannot be effectively pressed down into the solidifying adhesive.
This means that the carpet installer must be able to operate rapidly with the roller tool.
The roller tools shown in the Rice et al, the Norwegian and Walker patents all have a single axle with the two sections of the axle inclined at a fixed angle so that the roller tools, for purposes of drawing together of the material sections being worked, are unidirectional tools. Thus, with the Walker patent carpet seaming roller type rool the installer has to pick up the tool and carry or lift it back to the original starting point each time he wants to bring pressure to bear from the tool through the carpet to the underlying tape. This is a time consuming and generally impractical mode of operation for carpet seaming installations; and the prior art straight axle roller tool, which can be rolled back and forth along the seam without lifting from the face of the carpet, has been continued in use, even though this staight axle carpet roller tool does not produce any drawing together action on the seam.